The present invention relates to an image display device using a light valve element such as a liquid crystal panel to project an image onto a screen. In particular, the present invention relates to such an image display device as an LCD projector or a rear projection type display device.
An image display device such as an LCD projector or a rear projection type display device has been heretofore known. In such an image display device, light emitted from a light source such as an electric bulb is subjected to light intensity modulation for change into light and shade for each pixel in accordance with a video signal by use of a light valve means such as a liquid crystal panel, thereby forming an optical image, and the optical image is projected as a pictorial image on a larger scale onto a screen or the like.
As a light source means such as an electric bulb used in recent display devices, an electric-discharge lamp of a high power type is becoming popular. With an increase in luminance, there is a tendency to using a lamp of a higher power, while a demand exists for the reduction in size of the entire display device. Thus, cooling conditions for the lamp are becoming more and more strict. A reflector means for condensing light emitted from the lamp is disposed around the lamp. The lamp itself may degrade and burst as it is used. Therefore, the lamp is generally used in an enclosed state with reflector means and cover glass.
In such an enclosed state of the lamp, cooling of the lamp may be insufficient. As a countermeasure often adopted, cooling air is introduced from part of a reflector to cool the lamp to an appropriate temperature. In this case, part of the reflector is cut out and cooling air is introduced through the cutout portion. However, for example in the event of burst of the lamp, broken glass pieces of the lamp scatter from the cutout portion. To prevent the scattering, a net-like member is installed in the cutout portion in many cases. There also is known a display device wherein, in order to keep the temperature of a lamp appropriate, a cooling air guide plate is disposed near a cutout portion of a reflector, allowing cooling air to be directed to a desired portion of the lamp for cooling the lamp.
An example of conventional techniques for cooling this type of a lamp and for preventing the scattering of broken glass pieces upon burst of the lamp is a construction wherein cooling air is introduced into a reflection is disclosed, for example, in Japanese Patent Laid-open No. 7-168179. Further, Japanese Patent Laid-open No. 10-27518 discloses a construction wherein a direction of guiding cooling air into a reflector is controlled. Japanese Patent Laid-open No. 2000-200511 discloses separately a construction using a mesh means against bursting of a lamp and a construction of a cooling air guide plate. In particular, Japanese Patent Laid-open No. 2001-125195 discloses a construction wherein both a construction against bursting of a lamp and a construction for cooling air guide are compatible with each other.